They could probably be half the size of war hammers and be the largest one handed weapons that caused most damage, but were also the slowest. You would sheathe and unsheathe the hammers like you do with war axes. Perks would be things like having a 20 percent chance to stun with normal attacks from the hammers.
I just think that they would be frikin amazing. I mean, imagine a guy in full maxed out steel plate with dual enchanted one handed hammers. Awesome right? What are your thoughts and ideas?